Suncc49

03 Tahoe ECU w DBW on meth/water 93 octane... professionally tuned 3 weeks ago making tons of 6800 rpm dyno pulls fine on 13lbs 2bar china cobalt map sensor.

This just started happening last week.... at 4500rpm, timing retards to 3 with an afr pig rich below 10.5 and engine acts like it is hitting a rev limiter..... the DBW throttle position will be at 100% during this time, but it still backs all the timing out... IAT's go from 104 - 60 during this time, so the methanol is working

Car is tuned on speed density and here the OBII codes P0650 - , PO102 for maf delete , PO327 knock sensor 1 circuit low input bank 1 or single sensor (sensors were both replaced during my build)


I checked my plug gap this weekend thinking it was spark blowout and found some of my TR6's as high as .035 so I tossed in a new set and gapped them tighter...

Diagnosing this is tough with hp tuners logging capability, but I was hoping anyone had any suggestions on where I can troubleshoot before lugging the car back to the tuner....

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iTrader: (1)

If it's going that rich, it's going to act like a rev limiter. Here's where I'd start, (1) lower the boost down to a safe enough level that you can disable the meth kit and try it. (2) take that Chinese map sensor off and throw it as far as you can. (3) go get the map sensor and throw it again in the same direction you originally threw it and leave it there. I just had problems on my car with a "questionable quality" map sensor, never again.

Suncc49

Also getting Code 0327 Powertrain knock sensor 1 low input...... this definitely could be pulling timing. I bet my tuner didn't adjust sensitivity perhaps....

Chinese map sensor is trashed and new GM 2 bar in its place.

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iTrader: (1)

Sounds like you're onto it. Good luck and keep us posted.